1. Field of the Invention
The present invention relates to a cleaning sheet for a paper feeding device and, more particularly, to a cleaning sheet having a certain stiffness and coated with a cleaning adhesive (or an adhesive containing abrasive grain), which is set in a paper cassette to effectively clean a picker (paper feeding) roller when the roller rotates in contact with the cleaning paper.
2. Description of Related Art
The conventional cleaning sheet for feeding rollers in a printer or a copying machine is comprised of a thin sheet of paper with a coat of weak adhesive and covered with a releasable paper. The cleaning sheet, after removing the releasable paper therefrom, is placed in the paper cassette in the same way as the paper to be printed and is transported through a passage thereby cleaning the rollers.
As described above, the conventional cleaning sheet may not effectively clean a paper feeding roller. If the adhesive power of the sheet is increased, problems may occur such as jamming, damage to the ribbon, dead feeding etc. The conventional cleaning sheet has such drawbacks as it can be used only once and may not be automatically set to clean the roller.
The Japanese publication of the unexamined application No. JP, A, 58-82287 describes a conventional cleaning sheet for cleaning rollers which has a cleaning portion made of base paper having at least one side coated with an adhesive and a non-adhesive leading-paper portion which is continuous to the cleaning portion. The adhesive-coated portion of the cleaning sheet is covered with a releasable sheet of paper having a plurality of slits at specified intervals of width from one end to, at least, the center portion thereof.
The Japanese publication of the unexamined application No. JP, A, 3-54588 discloses another conventional cleaning sheet that is coated with a semi-adhesive coat and that may pass through rollers placed opposite to each other.
The Japanese publication of the unexamined application No. JP, U, 62-91671 discloses another conventional cleaning roller whereon a cleaning sheet, having perforations in it crosswise, is wound at least twice.
The Japanese publication of the unexamined application No. JP, U, 2-128155 discloses still another conventional cleaning sheet having both sides coated with an adhesive and covered with a releasable sheet of paper which can be fed from a manual feeding tray for cleaning passages for paper sheets.
The present invention relates to a cleaning sheet which is composed of a base sheet having enough stiffness not to protrude from a paper feeding cassette, a layer of cleaning adhesive applied to the base sheet and a releasable cover sheet laid on the adhesive layer, and the releasable cover sheet has a weak adhesive at its back end adhering to the reverse side of the last sheets of paper in the cassette and a strong adhesive at its front end adhering to the layer of cleaning adhesive on the base sheet.